FSC fire damper cartridges for circular duct mounting. Tested and classed EIS-60 or 120 (Integrity, Insulation and smoke leakage during 60 or 120 minutes) in accordance to the European standard EN-1366-2 at a constant pressure of 300Pa. Fire damper cartridges with shutting mechanism by thermal fusible link at 72ºC. An air-tightness joint prevents the propagation of smoke to low temperature, while the expanding joint is dilating to seal the fire damper cartridge.